Various surgical techniques may be used to repair a diseased or damaged heart valve, such as annuloplasty (contracting the valve annulus), quadrangular resection (narrowing the valve leaflets), commissurotomy (cutting the valve commissures to separate the valve leaflets), or decalcification of valve and annulus tissue. Alternatively, the diseased heart valve may be replaced by a prosthetic valve. Where replacement of a heart valve is indicated, the dysfunctional valve is typically removed and replaced with either a mechanical or tissue valve. Tissue valves are often preferred over mechanical valves because they typically do not require long-term treatment with anticoagulants.
A number of different strategies have been used to repair or replace a defective heart valve. Open-heart valve repair or replacement surgery is a long and tedious procedure and involves a gross thoracotomy, usually in the form of a median sternotomy. In this procedure, a saw or other cutting instrument is used to cut the sternum longitudinally and the two opposing halves of the anterior or ventral portion of the rib cage are spread apart. A large opening into the thoracic cavity is thus created, through which the surgeon may directly visualize and operate upon the heart and other thoracic contents. The patient must be placed on cardiopulmonary bypass for the duration of the surgery.
Open-chest valve replacement surgery has the benefit of permitting the direct implantation of the replacement valve at its intended site. This method, however, is highly invasive and often results in significant trauma, risk of complications, as well as extended hospitalization and painful recovery period for the patient.
Minimally invasive percutaneous valve replacement procedures have emerged as an alternative to open-chest surgery. Unlike open-heart procedures, this procedure indirect and involves intravascular catheterization from a femoral artery to the heart. Because the minimally invasive approach requires only a small incision, it allows for a faster recovery for the patient with less pain and bodily trauma. This, in turn, reduces the medical costs and the overall disruption to the life of the patient.
The use of a minimally invasive approach, however, introduces new complexities to surgery. An inherent difficulty in the minimally invasive percutaneous approach is the limited space that is available within the vasculature. Unlike open heart surgery, minimally invasive heart surgery offers a surgical field that is only as large as the diameter of a blood vessel. Consequently, the introduction of tools and prosthetic devices becomes a great deal more complicated. The device must be dimensioned and configured to permit it to be introduced into the vasculature, maneuvered therethrough, and positioned at a desired location. This may involve passage through significant convolutions at some distance from the initial point of introduction.
Accordingly, while heart valve surgery produces beneficial results for many patients, numerous others who might benefit from such surgery are unable or unwilling to undergo the trauma and risks of current techniques. Therefore, what is needed are methods and devices for performing heart valve repair and replacement as well as other procedures within the heart and great vessels of the heart that provide greater ease of access to the heart valves than the current minimally invasive techniques, while at the same time reducing the trauma, risks, recovery time and pain that accompany more invasive techniques.